Basic Photography Course

corrections are then sent through a translator device to
the printer. This system has essentially been replaced
with electronic darkrooms at Navy imaging facilities.

On-Easel Analyzers

An on-easel color analyzer (fig. 12-5) is an

electronic photometer used to measure the illumination

and three color primaries of light on the baseboard of

the enlarger. These photometers take these
measurements through tricolor filters.

On-easel measurements are made conveniently by

placing a small probe on the reference area of the
projected image on the baseboard. This small probe is
connected to a fiber-optic light tube that carries the light
from the reference area to the body of the photometer.

Color analyzers are programmed using standard

negatives printed by the trial-and-error method of color
printing. Once a good color print is made from the
standard negative, the image luminance of the master
negative is measured from the reference area. This
reference area is read through red, green, and blue
tricolor filtered sensors and finally without filters over
the photocell. The analyzer scale is then zeroed for each

condition. You then insert the new production negative
in the enlarger and place the photocell on the same
projected reference area on the easel. The aperture and
dichroic filters are then changed until the meter is zeroed
out once again.

Most on-easel color analyzers have a number of

memory channels so you can store programs for

different film or paper types.

The advantage of on-easel color analyzers is that,

unlike off-easel evaluation, each measurement
compensates for filter fading, lamp aging, and different
image magnifications. Exposure and filtration are given
directly. A disadvantage is that the readings must be
made under the same conditions as color printing on an

enlarger (complete darkness except for the illumination
of the projected image of the enlarger). Both on-easel
and off-easel evaluation depend strongly on accurate
readings and placement and choice of a good reference
area.

Two methods of electronically aided color

evaluation are used. They are spot or small-area
measurements and large-area or integrated measure-
ments. Small-area measurements made on the easel are
the most accurate; however, a small-reference area is not
always possible.

When small-reference areas are not provided,

large-area measurements can be taken. Large-area
measurements are made usually from the whole
negative area. For off-easel evaluation using a

Courtesty of Kreonite Inc.

302.262X

Figure 12-6.Kreonite color processor, Model KCP-16.

densitometer, a large photocell is used to take such
readings. For on-easel analyzers, the image is integrated
by placing diffusion material between the negative and
the photocell. You then place the photocell and sample
various areas of the projected image. These sample areas
are then "`integrated" to gray as though they were a

typical subject. This type of evaluation does not
compensate for images that do not contain typical color
or tonal distributions; for example, when the subject of
a negative is predominantly red, an integrated reading
overcompensates and a cyan print results. That is called
subject anomaly or subject failure. This is the method

used by many automatic printers. Color prints, such as
these, must be color corrected manually.

COLOR PRINT PROCESSING

Color printing paper must be handled and processed

in complete darkness because color paper is panchro-
matic. Like color film, time and solution temperature is
much more critical than in black-and-white processing.
Because the processing of color paper must be very
consistent, color prints are not processed in trays. Color
paper is always processed in automatic color print

processors (fig. 12-6) or rotary drum processors.

12-13

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Basic Photography Course

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DOFMaster for Windows On-line Depth of Field Calculator DOFMaster for Mobile Devices On-line Depth of Field Table Hyperfocal Distance Chart Articles FAQ Recommended Books Support Contact Links Home As an Amazon Associate I earn from qualifying purchases.	contents <- previous page next page -> corrections are then sent through a translator device to the printer. This system has essentially been replaced with electronic darkrooms at Navy imaging facilities. On-Easel Analyzers An on-easel color analyzer (fig. 12-5) is an electronic photometer used to measure the illumination and three color primaries of light on the baseboard of the enlarger. These photometers take these measurements through tricolor filters. On-easel measurements are made conveniently by placing a small probe on the reference area of the projected image on the baseboard. This small probe is connected to a fiber-optic light tube that carries the light from the reference area to the body of the photometer. Color analyzers are programmed using standard negatives printed by the trial-and-error method of color printing. Once a good color print is made from the standard negative, the image luminance of the master negative is measured from the reference area. This reference area is read through red, green, and blue tricolor filtered sensors and finally without filters over the photocell. The analyzer scale is then zeroed for each condition. You then insert the new production negative in the enlarger and place the photocell on the same projected reference area on the easel. The aperture and dichroic filters are then changed until the meter is zeroed out once again. Most on-easel color analyzers have a number of memory channels so you can store programs for different film or paper types. The advantage of on-easel color analyzers is that, unlike off-easel evaluation, each measurement compensates for filter fading, lamp aging, and different image magnifications. Exposure and filtration are given directly. A disadvantage is that the readings must be made under the same conditions as color printing on an enlarger (complete darkness except for the illumination of the projected image of the enlarger). Both on-easel and off-easel evaluation depend strongly on accurate readings and placement and choice of a good reference area. Two methods of electronically aided color evaluation are used. They are spot or small-area measurements and large-area or integrated measure- ments. Small-area measurements made on the easel are the most accurate; however, a small-reference area is not always possible. When small-reference areas are not provided, large-area measurements can be taken. Large-area measurements are made usually from the whole negative area. For off-easel evaluation using a Courtesty of Kreonite Inc. 302.262X Figure 12-6.Kreonite color processor, Model KCP-16. densitometer, a large photocell is used to take such readings. For on-easel analyzers, the image is integrated by placing diffusion material between the negative and the photocell. You then place the photocell and sample various areas of the projected image. These sample areas are then "`integrated" to gray as though they were a typical subject. This type of evaluation does not compensate for images that do not contain typical color or tonal distributions; for example, when the subject of a negative is predominantly red, an integrated reading overcompensates and a cyan print results. That is called subject anomaly or subject failure. This is the method used by many automatic printers. Color prints, such as these, must be color corrected manually. COLOR PRINT PROCESSING Color printing paper must be handled and processed in complete darkness because color paper is panchro- matic. Like color film, time and solution temperature is much more critical than in black-and-white processing. Because the processing of color paper must be very consistent, color prints are not processed in trays. Color paper is always processed in automatic color print processors (fig. 12-6) or rotary drum processors. 12-13 contents Basic Photography Course <- previous page next page ->	As an Amazon Associate I earn from qualifying purchases.
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